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. 2004 Oct 1;18(19):2404–2417. doi: 10.1101/gad.1230704

Figure 1.

Figure 1.

Expression of Wnt genes correlates with the expression of the joint marker Gdf5, up-regulation of β-catenin protein, and down-regulation of Sox9 expression. (A) Whole-mount in situ hybridizations. At 11.5 dpc, Wnt14 and Gdf5 were expressed in the future shoulder and elbow joints (arrows). Gdf5 was also expressed in the distal limb bud, whereas Wnt14 was also expressed in the mesenchymal cells surrounding the forming cartilage. Wnt16 was expressed in the future MTP joints (arrow). At 12.5 dpc, Wnt14 was still expressed around the cartilage, but stronger expression was detected in the forming joints (arrows). Gdf5 was expressed in all developing joints (arrow) and the interdigital area. The MTP region was expanded and Wnt16 was expressed in the forming MTP joints (arrow). Joint-specific Wnt4 expression detected by whole-mount in situ hybridization was obscure at 11.5 or 12.5 dpc due to its expression in the surface ectoderm and tissues around the cartilage. (B) A limb bud section at 11.5 dpc hybridized with a 35S-labeled Gdf5 probe is shown as a bright-field image. The boxed elbow region was enlarged, and expression of Gdf5, Wnt14, and Wnt4 (arrowheads) was detected in consecutive sections. Wnt14 and Wnt4 were also expressed at stronger levels in the mesenchyme surrounding the forming cartilage (arrows) than in the presumptive joint (arrowheads). Immunohistochemistry of β-catenin and Sox9 was performed on a consecutive section. β-Catenin was up-regulated in the future joint region (arrowhead). The boxed region was enlarged in an inset to show a cell with nuclear localized β-catenin protein (arrow). Sox9 was detected in the forming cartilage (arrow), but down-regulated in the forming joint (arrowhead). (H) Humerus; (R) radius; (U) ulna. (C) Expression of Gdf5, Wnt14, Wnt4, and Wnt16 was all detected in the developing joints between phalanges (P) at 13.5 dpc (arrows). Expression of Wnt16 in the MTP joints was much stronger than Wnt14 and Wnt4. (D) Only Gdf5 and Wnt14 expression was detected in the elbow joint at 13.5 dpc (arrows). Gdf5 and Wnt4 were also expressed in the future joint capsule region (arrowhead). Wnt14 was also expressed in the future tendons (arrowhead). Complementary patterns of β-catenin and Sox9 protein levels in the joint were similar to those in B.